Israeli researchers have developed an interface that can be controlled by breathing through the nose. This technology could be used to help people with limited mobility gain more independence:

The "sniff controller," as it is known, is worn externally via a rubber tube not unlike the ones often used in hospitals for patients who need oxygen. The nasal device is not universal, as about a quarter of all people in a healthy control group were found to have insufficient volitional control over their soft palate, the part of your nasal passageway that lets you regulate the strength of your sniffs. But for those with sufficient soft palate control, the sniff controller gave test subjects a new degree of freedom.[...]

The team also created an interface for controlling an electric wheelchair using the sniff detector (two successive sniffs in = forward, two successive sniffs out = backward, etc.) and tested it on ten healthy patients. Again, they found that after a bit of practice the control group could easily navigate the wheelchair, so they put a man paralyzed from the neck down in the driver's seat. To their amazement, they found that after just 15 minutes a paraplegic can become quite skilled at navigating a wheelchair using the sniff detector.

Okay, I like the idea and all... but I sniff all the time. I have sniffed three times since I have read this. What about that? I guess you have to control your runny noses and allergies pretty agressively...